Types of Scales in Engineering Drawing

Types of Scales Points : Types of Scales in engineering drawing, Plain Scale, Diagonal Scales, Comparative Scale, Vernier Scale, Scale of Chords Scales are classified as:
1. Plain Scale
2. Diagonal Scales
3. Comparative Scale
4. Vernier Scale
5. Scale of Chords 1. Plain Scale Plain scale is cleanly a line which is separated into a proper number of equal parts, first of which is further sub-divided into small parts. It is use to represent either two units or a unit or a unit and its fraction for example km and hm, m and dm, cm and mm etc.

2. Diagonal Scales Diagonal scale is use to signify three units. i.e., main unit, its sub-unit and further sub-division of subunit. Such as, a diagonal scale can signify (a) metres, decimetres and centimetres (b) kilometre, hectometre and decameter (c) yards, feet and inches and so on. Sub-division of small unit of a plain scale is prepared by diagonal principal. As third unit of scale is calculated by the help of this diagonal the scale is being name as diagonal scale.

3. Comparative Scale Comparative scales are scales by similar representative fraction but graduate to examine dissimilar units. A map or a drawing drawn by a scale reading miles and furlongs can be calculated off directly in kilometers and hectometers through a comparative scale construct by same representative fraction. Comparative scales can be construct as plain scales or diagonal scales depending upon necessity.

4. Vernier Scale A tool used for measure fractional part of one of smallest divisions of a graduate scale. It generally consists of a little auxiliary scale which slides next to of the major scale. Slightest count of the vernier = the difference between smallest division on major division and smallest division on vernier scale.

5. Scale of Chords In absence of a protractor, a scale of chords can be use to calculate angle or to set necessary angle. The construction is base on lengths of chords of angles measured on the similar arc.